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  View original topic: Need help with 1981 after rebuild.
mcnajason Mon Aug 29, 2016 3:08 pm

Hey guys, just rebuilt my stock 2000cc. Replaced all bearings, cylinders,jugs,pistons,rings,heads, rods, lifters and all seals. Everything in the case measured up good. The bus was running O.K before the rebuild and reason for rebuild was low compression on 2 cylinders (80psi). Now that i have rebuilt the engine and its in the bus, It will only start with full throtlle. Then runs very rough. There seams to be a hissing, possibly a vacuum leak. Altho all the hoses are connected and i have not been able to find any leaks using brake cleaner. I have run a compression, the engine was not at running temp altho not cold. 145-150psi across the board with a well known compression tester. The engine is running very rough and i cant seem to keep it alive or let it idle. i Have static timed the engine and it seems like ignition timing is o.k. Spark is there. Fuel filter changed.

1. Is my compression too high? Bentley states 87-131psi. I did not use the cylinder to head gasket in my kit as ive read not to use them on AMC heads.

2. Would 150 psi make it so my bus runs very rough and need full throttle to start?

Any ideals would be greatly appreciated guys!

djkeev Mon Aug 29, 2016 3:23 pm

Find the vacuum leak, fix it.

Intake seals?
Open hose port?
Power brake line disconnected?
??????

Dave

Mellow Yellow 74 Mon Aug 29, 2016 3:47 pm

Could be the timing is way out - check you haven't installed the distributor 180 degrees out and then do the static timing before starting.

Also I wouldn't use brake cleaner on the engine - it is a fairly aggressive product.

the joker Mon Aug 29, 2016 3:49 pm

yes
yes
yes
yes

you have a massive leak
somewhere
after rebuilds double chk every thing
something loose or missing

mcnajason Mon Aug 29, 2016 5:29 pm

Ive checked the timing multiple times, the distributor is on the proper way and not 180 as per the 3 manuals and have and pics on thesamba. Ive checked and checked and checked for vacuum leaks and cant find anything. Could my compression be too high? 150psi? I dont belive that this would cause it to run soo rough though.

djkeev Mon Aug 29, 2016 7:49 pm

Ok.....

STOP!

Take a deep breath, clear your brain and relax.

Now think.
"If this Van was dragged into my shop and I knew nothing about it, where would I begin?"

Answer.
Compression. You say you have 150? All close to that? Good! Stop worrying about it.

Fuel. Do you have fuel being delivered?
If not, fix it.

Spark. Not only do you check if you have spark, is the spark being delivered in the right spot at the right time?

Check this, ASSUME NOTHING! The only unknown fear is that you didn't line up the timing marks on the crank gear and cam gear. We can't deal with this.

Rotate the engine by hand to TDC, is #1 on TDC or #3? (Same TDC mark)
You MUST Find out.
How?
Pop #1 valve cover and look at the rocker arms, are they both up and at the same level or is the exhaust (outer valve stem) depressed?
If it is depressed rotate the engine one full rotation to TDC again. Both valve stems should be at the same level.

Now, pop the distributor cap, where is the rotor pointing?
Look at the cap, when reinstalled, does the rotor point to the wire terminal that goes to cylinder #1?

If it does, visualize clockwise, the next terminal goes to #4, next #3 and finally #2.
Don't assume they do, follow each wire to the plug, some of us have overlooked such a simple thing and gone on for a week fighting a bad running engine only to later find the plug wires screwed up! :oops: who would do THAT?!?
Anyway....
Are the wires correct?

Report back.

Dave

mthielk Mon Aug 29, 2016 8:40 pm

You know when the valve covers are off a huge vacuum leak is created through the breather. It is probably something simple like that.

mcnajason Mon Aug 29, 2016 8:47 pm

Thanks for the reply Dave, I did line up the cam/crank when i put the engine together. Installed the dizy and gear when cylinder #1 was on TDC on compression. This was when the case was split. I could see both cam lobes opening a valve on the #3 cylinder while both were at TDC. I double checked once i was having this issue by holding my thumb against the spark plug hole while coming up on cyl #1 TDC. Its defiantly on cyl#1 TDC compression. Checked wiring again to all plugs. They are all in proper location. Ive done the timing once again. Static timing is O.K.

I will be looking into the fuel system tomorrow, I dont have a fuel pressure
guage on hand but may be able to make something work.

Another possibility- I purchased after market lifters, to bleed them i left them in oil overnight. Then used a pushrod and compressed the lifters one by one for about 5 minutes each while submerged in oil. They got stiffer but not hard as a rock. I was still able to push them down a bit with my thumb. I then did the flush to 1.5 turns for vavle adjustment. Could this be my problem?

mcnajason Mon Aug 29, 2016 8:54 pm

mthielk wrote: You know when the valve covers are off a huge vacuum leak is created through the breather. It is probably something simple like that.

Im sorry mthielk, I dont understand. My valve covers are on when running. Please explain.

mthielk Mon Aug 29, 2016 11:34 pm

I just thought you might be running without the valve covers, I have done that occasionally while getting the engine set up. Some oil leaks out but the problem is these engines run with low pressure in the crank case, when you leave the covers off it causes a lot of air to pass into the crank case through the open valve cover and through the breather hose into the intake and it bypasses the air flow meter. The controller thinks there is a small amount of air going into the engine but in reality there is a lot and the engine runs terrible.

mikemtnbike Tue Aug 30, 2016 6:12 am

mcnajason wrote:

I will be looking into the fuel system tomorrow, I dont have a fuel pressure
guage on hand but may be able to make something work.



I don't know about Canadian tire or whatever FLAPS you use, but I used the fuel pressure gauge Oreilly's had in their loaner tool program down here stateside. Maybe your FLAPS has a similar program.

Synthead Tue Aug 30, 2016 10:19 pm


weswsimpson Thu Sep 01, 2016 12:32 pm

Do yourself a favor, and get an inspection camera if you don't have one and stick it in the spark plug holes, watch your valves open and close... if they don't open when they should, or only a little, then you need to adjust your valves. Just because your engine has hydraulic lifters, doesn't mean they don't need to be adjusted correctly. If the lifters have bled-down and have air in them it will be obvious when you watch your valves open and close with the camera. It's not going to run right if the valves aren't adjusted correctly. Search elsewhere on this site for information on valve adjustment and bleeding lifters or go to ratwell's site.

http://www.harborfreight.com/digital-inspection-camera-61839.html

mcnajason Fri Oct 07, 2016 7:52 pm

Hey guys thanks for all the help! After performing more diag, checking fuel pressure, ignition, timing and spending countless hours of overthinking, I stumbled upon the Injector signal wire not being plugged into its proper location. It then started up and has been running for the last 2000km.
In the last 2000km I did find some issues
- oil leak on the left side from pushrod tube seals
- Oil leak from the bell housing (must be rear main, I replaced it with new when build the engine)
- Very very randomly it will bog on the HWY when going 100km/h for over 1.5 Hours.

So Today I pulled the engine out once again to replace:
- Rear main
- Intake boots
- oil cooler
- Pushrod tube seals
- Oil pump
- Add a oil pressure sender
- Tune-up



My connector that clips into the thermos switch is broken, and has previously been RTV'd on to hold into place. Anyone know where to order this connector?

a1fa Fri Oct 07, 2016 8:00 pm

It's a Bosch EV1 connector. You can get them from any car parts store (may have to order online), or ebay.

mrcool Mon Oct 24, 2016 4:39 pm

Did you ever find out what that hissing was? Is it coming from the inspection port for the fly wheel?

mcnajason Mon Oct 24, 2016 6:56 pm

No, have not had time to tackle that yet. Where is the inspection port located?

mrcool Mon Oct 24, 2016 7:11 pm

if youre looking at the engine from the back of the van it is down below the intake plenum on the left side. It is a circle about the size of a dollar coin.

mcnajason Tue Oct 25, 2016 6:37 pm

Thanks mrcool, Ill take a look this weekend.



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